Chemical Cleaning of Cooling Water system line
Chemical Cleaning of Cooling Water system line
(OP)
Hi all,
curently i am studying in posibillity to do a chemical cleaning in cooling water system to remove it scale. When i say cooling water system it means the whole system, incuding all piping and all hot equipment passed by the cooling water.
The cooling water is sweet water downstream clarifier and sand filter.
We planned to do it with sulfuric acid, the concentration around 3%-5%. And part of our idea is how if we do it online (plant is still running).
I still have a lot of doubt, since there is no acid chemical that can really remove all the scale and a lot of diversity material that exposed in this chemical cleaning. I also never heard that anyone ever do it before makes it seems a crazy idea but worthed to studied.
My question :
1.does anyone in this forum ever do this chemical cleaning?what are your opinion?
2.what scale usually occurred in sweet cooling water line? (i supposed it mix of calcium carbonat, silica and dominate with corrosive product scale)
3. What chemical suitable for those scale?
4. Some of the material resistancy data to sulfuric acid can be found in corrosion handbook. but some are not (like tungsten carbon in pump mech seal, and some special metal) where can i find that data?
thanks before....
Devax rayz
curently i am studying in posibillity to do a chemical cleaning in cooling water system to remove it scale. When i say cooling water system it means the whole system, incuding all piping and all hot equipment passed by the cooling water.
The cooling water is sweet water downstream clarifier and sand filter.
We planned to do it with sulfuric acid, the concentration around 3%-5%. And part of our idea is how if we do it online (plant is still running).
I still have a lot of doubt, since there is no acid chemical that can really remove all the scale and a lot of diversity material that exposed in this chemical cleaning. I also never heard that anyone ever do it before makes it seems a crazy idea but worthed to studied.
My question :
1.does anyone in this forum ever do this chemical cleaning?what are your opinion?
2.what scale usually occurred in sweet cooling water line? (i supposed it mix of calcium carbonat, silica and dominate with corrosive product scale)
3. What chemical suitable for those scale?
4. Some of the material resistancy data to sulfuric acid can be found in corrosion handbook. but some are not (like tungsten carbon in pump mech seal, and some special metal) where can i find that data?
thanks before....
Devax rayz





RE: Chemical Cleaning of Cooling Water system line
2. It depends on the water chemistry and materials of construction in the system. You could have the scales you mention or it could be tuberculation. See http://w
3. You might consider other chemicals such as sulfamic acid, EDTA, etc. that might be a bit safer to deal with.
4. Have you considered how you will determine that the cleaning is completed?
5. Don't forget to look at the impact of the cleaning agents on the cooling tower materials of construction.
6. Waste disposal will be an issue to address.
7. Have you developed a plan to passivate the surfaces after cleaning?
RE: Chemical Cleaning of Cooling Water system line
You should isolate sections and use a small pump to provide circualtion of the acid.
Sulfamic or phosphoric with EDTA added will be easier on most materials and keep the prodicts in solution.
You will need to monitor the cleaning and determine the end point.
One place to start is www.oakite.com
= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.
http://www.trenttube.com/Trent/tech_form.htm
RE: Chemical Cleaning of Cooling Water system line
No chemical treating company or pipe cleaning company (using rams or pulsed jets of water, which would be a noisy process) would accept liability for any damages resulting from loosened pipe scale/corrosion/debris.
RE: Chemical Cleaning of Cooling Water system line
I have done some work with a company called BJ Services doing chemical cleaning on equipment similar to yours. They can provide an evaluation and offer cleaning options. If interested you can call Larry Slabodnic at 909-357-8054.
Hope this helps
Chris Derrick
RE: Chemical Cleaning of Cooling Water system line
If you already plan to reduce rates during the cleaning, it is better I think to just shutdown for 5 days and do a good safe job. You can also open the equipment and inspect your work. Hopefully the increased production possible with clean equipment will allow you to make-up for lost production over the subsequent month.
Best of luck, sshep
RE: Chemical Cleaning of Cooling Water system line
The majority of scale species are obviously waterborne deposits, mainly calcium carbonate, iron oxide (usually hematite or goetite), silica scales, and on occasion sulfates if sulfuric acid is used in the plant's pH adjustment process.
There are a variety of solvents that would be effective on the common mix of scales, but I would not use sulfuric acid on these systems. The likelihood of creating calcium sulfate (as a precipitate) will foul your system extensively - as not all of it ends up in the CW basin. You would not want to route the cooling water/solvent mixture back to the CW tower anyway, as once you solubilize or sequester iron, the aeration that occurs can potentially yield a ferric condition, which is extremely corrosive to your equipment.
There are additives and techniques available to design an ideal cleaning process. On-line cleaning to restore your dT across heat exchange equipment is often a simple and effective method that allows the acid or chelant to be injected upstream of the exchanger(s) and a neutralization agent introduced downstream to assure the pH is controlled. Depending on the choice of solvent, nature of scale, and configuration of equipment, the wastes resulting from the on-line cleaning process can usually be captured and contained via filtration of the CW basin or return sump areas, so as not to redistribute any precipitated materials back into the CW supply piping.
If the plant is going to be totally shut down during your outage, sections or segments of the piping and assocated exchangers can be cleaned via circulation of chemicals, high energy flushing, or mechanical (hydrojetting) processes. It is often the case that in the larger diameter piping systems, there is often a lot of solids contamination from airborne dirt, sand, etc. that is slowly pushed around the system. Flushing at high velocities usually motivates this contamination from within the system.
Recommended solvents are:
Inhibited hydroxyacetic/formic acid blends
Inhibited hydrochloric acid with fluoride additives (for silicates)
Inhibited formic acid
Inhibited sulfamic acid
Inhibited EDTA/sulfamic acid blends
Inhibited low-pH EDTA (disodium or diammonium salts)
Convential solvents I would NOT recommend:
Sulfuric acid - due to potential for calcium sulfate precipitation
Citric acid - due to potential for calcium citrate precipitation
HTH
Lee